How to interpret return type shown by Cthulhu?

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Looking at the output of @descend_code_warntype reduce(vcat, eachcol(rand(2,2))) on nightly, I find

Advanced: dump [P]arams cache.
   %69 = invoke throw_boundserror(::Matrix{Float64},::Tuple{Base.Slice{Base.OneTo{Int64}}, Int64})::Union{}
   %141 = invoke throw_setindex_mismatch(::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true},::Tuple{Int64})::Union{}
 • %153 = invoke copyto!(::Matrix{Float64},::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true})::Any
   ↩

The return type of copyto! is inferred as Any. However, if I select the call, I find

copyto!(dest::AbstractArray, src::AbstractArray) @ Base abstractarray.jl:1044
Body::Matrix{Float64}
1045 1 ─ %1  = Base.getfield(src, :indices)::Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}                                                   │╻╷╷╷╷   isempty
     │   %2  = Core.getfield(%1, 1)::Base.Slice{Base.OneTo{Int64}}                                                                         ││┃││     length
     │   %3  = Base.getfield(%2, :indices)::Base.OneTo{Int64}                                                                              │││┃││╷╷   size
     │   %4  = Base.getfield(%3, :stop)::Int64                                                                                             ││││╻╷      map
     │   %5  = (%4 === 0)::Bool                                                                                                            ││╻       ==
     └──       goto #3 if not %5                                                                                                           │       
     2 ─       return dest                                                                                                                 │       
     3 ─       nothing                                                                                                                     │       
1050 4 ─ %9  = invoke Base.unalias(dest::Matrix{Float64}, src::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true})::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true}
1051 │   %10 = invoke Base.copyto_unaliased!($(QuoteNode(IndexLinear()))::IndexLinear, dest::Matrix{Float64}, $(QuoteNode(IndexLinear()))::IndexLinear, %9::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true})::Matrix{Float64}
     └──       return %10                                                                                                                  │       
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Advanced: dump [P]arams cache.
 • %9 = invoke unalias(::Matrix{Float64},::SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true})::…
   %10 = invoke copyto_unaliased!(::IndexLinear,::Array{…},::IndexLinear,::SubArray{…})::Matrix{Float64}
   ↩

In this, the return type seems to be concretely inferred as Matrix{Float64}. How do I interpret the return type displayed in the parent call?